The conventional axle driving apparatus which constructs an axle casing by coupling an upper half casing and a lower half casing which are dividable along the axis of axle shaft, and mounts in the axle casing in relation of approximately aligning the axis of motor shaft with the joint surface of casing a center section for vertically mounting a hydraulic pump and horizontally mounting a hydraulic motor, is well known as disclosed in the Japanese Utility Model Laid-Open Gazette Hei 1-154358, Patent Laid-Open Gazette Hei 1-309821 and Specification of U.S. Pat. Nos. 4,914,907, 4,932,209 and 4,903,545.